Title : THE SPECTRA OF AQUEOUS POLYSULFIDE SOLUTIONS. I. THE RESOLUTION INTO TRANSITION ENERGY BANDS. II. THE EFFECT OF ALKALINITY AND STOICHIOMETRIC COMPOSITION AT EQUILIBRIUM,

Corporate Author : SVENSKA TRAFORSKNINGSINSTITUTET STOCKHOLM

Personal Author(s) : Teder,Ants

Report Date : 23 APR 1969

Pagination or Media Count : 39

Abstract : I. The spectra of polysulfide solutions, of different alkalinity and with different ratios between polysulfide excess sulfur and sulfide sulfur, have been studied at 25C and 80C. Sulfide sulfur here means all sulfur in oxidation state (-2), while excess sulfur stands for sulfur in polysulfide ions formally in oxidation state 0. The solutions could be investigated without dilution from 200 nm to 600 nm wavelength in spite of the absorbance varying more than three powers of ten. The spectra obtained could be resolved into eight overlapping bands with normally distributed transition energies. One of the bands seems to be connected with HS(-) ions while five solely and two mainly are connected with different polysulfide ions. II. The absorptivities, at eight selected wavenumbers, of a great number of polysulfide solutions of different alkalinity and with different ratios between polysulfide excess sulfur and sulfide sulfur, X(s), have been determined at 25C and 80C. The equilibria in aqueous polysulfide solutions were analyzed using the method of corresponding solutions and the computer program LETAGROP respectively. The intensities of the absorption bands varied systematically with (HS(-)(OH(-)/(S(0)). Several polysulfide ions seem to contribute to each band. The presence of the ions S3S(2-), S4S(2-) and S5S(2-) was found to be statistically significant. Several different assumptions regarding the smaller and larger ions present could describe the system almost equally well. Tentative equilibrium constants are proposed. (Author)